Thomas Henry Huxley (1825-1895) was one of the intellectual giants of Victorian England. Initially a surgeon by training, he became the principal exponent of Darwinism and popularizer of "scientific naturalism." His public advocacy of evolution, the voice he gave to science as a dignified and vital profession, the powerful offices he held in its societies, and the many volumes he published of and about science made Huxley among the most influential of all nineteenth-century figures in the history of science.

Huxley was a prolific essayist, and his writings put him at the center of...